I found it a month ago in a used bookstore in Manhattan. Four handwritten pages on 9 by 11 sheets. “I’m so sorry about your father, Suzanne . . . I registered Q in public school a week ago . . . Maeve is trying awfully hard to talk . . . The recession is making an impact on New York . . . Steve and I are going to a concert February 20th.”

The letter was dated Feb. 18, 1991. Feb. 18 is my birthday. I would have read the letter anyway, but maybe not so eagerly. And maybe not right then. But I felt an immediate connection and a certainty, as I sat on the floor and studied every word, that this letter, so full of warmth and news and love and wonder, had never been mailed.

The writer lived in Manhattan. Its intended recipients lived in Wichita. If the letter had reached its rightful owners, wouldn’t it have ended up in Kansas, not New York? Unless, of course, Suzanne and John had later moved to New York.

A few weeks ago, I wrote about this letter and its mystery. I wrote hoping that someone would know something about a Suzanne and John who lived in Wichita in 1991. Or about the letter writer, Mary or Nancy (I could not make out the signature). Or about her husband, Steve, who worked on Broadway shows, or about their children, Quentin and Maeve. I had Googled and Facebooked all of these people, had searched and searched, but came up with nothing.

But someone else did.

A reader e-mailed to me an obituary that ran in the Wichita Eagle.

“Carver, Mary Blake, born May 19, 1951, passed away Sunday, June 23, 2013, in New York City, where she lived her entire adult life.”

This was not the news I expected. In the letter, Mary was getting Quentin ready for first grade. She was just pushing Maeve on a swing in the park. She was looking forward to seeing Hall and Oates with her husband.

Mary Blake Carver had grown up in Wichita. She was an actress and a singer who moved to New York and got her actor’s equity card, the obituary said.

Then there was this: Memorials were to be sent to the Alzheimer’s Association.

My oldest childhood friend died of Alzheimer’s when she was 63. And I was reading all this the day before her 67th birthday.

Soon, an e-mail arrived from another reader.

On March 29, 2007, The New York Times had written a story featuring Mary. “Living with Alzheimer’s Before a Window Closes.” It begins with these words: “Mary Blake Carver gazes from the cover of a neurology magazine this month, under the headline ‘I’m Still Here!’ She often feels like shouting the message to her friends, her children, her husband.”

She was only 55 then. And already, she couldn’t keep up with conversations, couldn’t work, couldn’t button her coat, and was losing more of herself every day.

Her letter, written 16 years before that article, is perfectly structured and infused with love and hope for her husband and children and friends. And it’s full of fear, too. About her children’s future and about the world.

And all of it, the hope, fear, love, reverie, every memory is dearer now, found words, precious words, every word she wrote.

I found Suzanne and John Miller in Woodland Park, Colo. I phoned and read the letter to Suzanne. I learned from Suzanne that Mary rented an apartment on 80th Street when she first came to New York. When she and Steve married, they bought the apartment. It’s a half-block from where my son and his family live. I have walked past it at least 100 times.

After speaking with Suzanne, I made a copy of the letter, then put it in the mail.

To see a friend’s handwriting, to read an old friend’s words, to remember who you were and who she used to be.

Such unexpected gifts.

“What I’m really trying to say is I love you and wish you all the strength you need and all the love you need,” Mary wrote in 1991.